[clang] [CIR] Upstream support for emitting ignored statements (PR #130869)

[Andy Kaylor via cfe-commits]

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@@ -0,0 +1,53 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=LLVM
+
+int f1(int i);
+
+int f1(int i) {
+  i;
+  return i;
+}
+
+//      CIR: module
+// CIR-NEXT: cir.func @f1(%arg0: !cir.int<s, 32> loc({{.*}})) -> !cir.int<s, 32>
+// CIR-NEXT:   %[[I_PTR:.*]] = cir.alloca !cir.int<s, 32>, !cir.ptr<!cir.int<s, 32>>, ["i", init] {alignment = 4 : i64}
+// CIR-NEXT:   cir.store %arg0, %[[I_PTR]] : !cir.int<s, 32>, !cir.ptr<!cir.int<s, 32>>
+// CIR-NEXT:   %[[I_IGNORED:.*]] = cir.load %[[I_PTR]] : !cir.ptr<!cir.int<s, 32>>, !cir.int<s, 32>
+// CIR-NEXT:   %[[I:.*]] = cir.load %[[I_PTR]] : !cir.ptr<!cir.int<s, 32>>, !cir.int<s, 32>
+// CIR-NEXT:   cir.return %[[I]] : !cir.int<s, 32>
+
+//      LLVM: define i32 @f1(i32 %[[I:.*]])
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andykaylor wrote:

That's lowering through clangir to llvm ir.

https://github.com/llvm/llvm-project/pull/130869